Over the last few years, the public has gradually become aware of the existence of a new cause: animal liberation. Most people first heard of the movement through newspaper articles, often of the "what on earth will they come up with next?" variety. Then there were marches and demonstrations against factory farming, animal experimentation or the Canadian seal slaughter; all brought to an audience of millions by the TV cameras. Finally there have been the illegal acts: slogans daubed on fur shops, laboratories broken into and animals rescued. What are the ideas behind the animal liberation movement, and where is it heading? In this essay I shall try to answer these questions.